Process for the alkylation of phosphorus-containing compounds

ABSTRACT

A process for alkylating a phosphorus-containing compound to provide an alkylated phosphorus-containing compound is provided which comprises alkylating 5 phosphorus-containing compound possessing at least one phosphorus-hydrogen alkylatable site with reactant which generates alkene and/or cycloalkene alkylating agent in situ in the presence of initiator, the alkylene and/or cycloalkylene alkylating agent alkylating the phosphorus-containing component to provide alkylated phosphorus-containing product.

CROSS REFERENCE TO RELATED APPLICATION

This invention claims the benefit of U.S. provisional application Ser.No. 60/564,801, filed Apr. 23, 2004, the entire contents of which areincorporated by reference herein.

BACKGROUND OF THE INVENTION

This invention relates to processes for alkylating phosphorus-containingcompounds. More particularly, this invention relates to processes foralkylating phosphorus-containing compounds possessing at least onephosphorus-hydrogen

alkylatable site to provide an alkylated phosphorus-containing product,e.g., a mono- or dialkylphosphinic acid or metal salt thereof, analkylarylphosphinic acid or metal salt thereof, an alkyl alkylphosphonicacid or metal salt thereof, an alkyl or aryl dialkylphosphinate ester,an alkyl or aryl alkylarylphosphinate ester, an alkyl orarylalkylphosphorous acid or metal salt thereof or a dialkyl or diarylalkylphosphonate ester.

In order to prepare dialkylphosphinic acid derivatives, a complexsynthesis route has been used which includes the hydrolysis ofmethyldichlorophosphine to provide methylphosphinic acid and thesubsequent esterification of this acid to provide an alkylmethylphosphinic ester. The second phosphorus-hydrogen bond can also bealkylated in the presence of a free-radical initiator.

The use of dialkylphosphinic acid derivatives as flame retardants forpolyesters (poly(ethylene terephthalate) and polybutyleneterephthalate)) is described in European Patent Publication No. 699,708.These products are synthesized by a complex process usingmethyldichlorophosphine which is hydrolyzed to methylphosphinic acid;the ester of this acid has been prepared and isolated as intermediate.To prepare dialkylphosphinic acids or derivatives thereof,alkylphosphinic esters can be alkylated by α-olefins at hightemperatures under free-radical catalysis conditions. In the case of thereaction of alkylphosphinic acids under the same conditions, only thedisproportionation products, namely, alkylphosphines and alkylphosphonicacids, are obtained while under mild conditions no reaction is observed.

U.S. Pat. No. 4,632,741 describes a process for preparing mixtures ofsalts of alkylphosphinic and dialkylphosphinic acids by reacting anolefin with a salt of hypophosphorous acid in the presence of aphotoinitiator using UV light. U.S. Pat. No. 4,590,014 describes asimilar process in which the olefin is reacted with the alkali metalsalt of hypophosphorous acid in the presence of a free-radicalinitiator. However, the predominant product monoalkylphosphinic acid.

U.S. Pat. No. 6,300,516 describes a process for preparingdialkylphosphinic acids and/or alkali metal salts thereof by reactingolefins, particularly ethylene, with alkylphosphinic acid orhypophosphorous acid in the presence of azo free-radical initiator. Thisprocess is performed in a pressurized reactor with complicated feedingsystems which require special safety features. Only high boiling olefinscan be reacted with hypophosphorous acid at atmospheric pressure.

The reaction of hypophosphorous acid with isobutene was reported in theliterature (S. Deprele and J-L. Montchamp, J. Org. Chem. 2001, 66,6745). The reaction was run in the presence of a stoichiometric amountof triethyl borane as initiator. The yield of monosubstitutedisobutylphosphinic acid was only 38%.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a process for the alkylationof phosphorous-containing compounds possessing at least onephosphorus-hydrogen

alkylatable site.

It is a particular object of the present invention to provide such aprocess employing as alkylating agents short chain alkyls which resultwithin a relatively short time in a high yield of the desired alkylatedproduct while avoiding the aforenoted disadvantages associates with theknown processes discussed above.

These and other objects of the invention are achieved by the process ofalkylation herein which comprises alkylating phosphorous-containingcompound possessing at least one phosphorus-hydrogen

alkylatable site with reactant which generates alkene and/or cycloalkenealkylating agent in situ in the presence of free radical initiator, thealkene and/or cycloalkene alkylating agent alkylating thephosphorus-containing compound to provide alkylatedphosphorus-containing product.

Without intending to be bound, it is thought that the reactant whichgenerates alkene or cycloalkene in situ under alkylation conditionsproduces a sufficient concentration of these compounds that will resultin alkylation of the at least one phosphorus-hydrogen alkylatable sitepresent in the starting organophosphorous-containing compound and as thealkenes/cycloalkenes are consumed in the alkylation reaction, theequilibrium shifts towards generation of additionalalkenes/cycloalkenes.

DETAILED DESCRIPTION OF THE INVENTION

The phosphorus-containing compound employed as one of the startingreactants herein must contain at least one phosphorus-hydrogen

alkylatable site and can contain more than one such site in which casethe alkylated phosphorus-containing product may either be partially orfully alkylated.

In one embodiment of the invention, the phosphorus-containing startingreactant is represented by the general formula (I):

wherein:x¹, where present, is

and x², where present, is

in which R¹ is H, alkyl of up to 30 carbon atoms, cycloalkyl of from 3to 12 carbon atoms or aryl of from 6 to 20 carbon atoms; Me is a metalhaving a valence v of 1, 2, 3 or 4; R² is H, alkyl of up to 30 carbonatoms, cycloalkyl of from 3 to 12 carbon atoms or aryl of from 6 to 20carbon atoms; and,a, b, c, d, e and f each independently is 0 or 1,provided,when a=1, c=1 and b=0,when b=1, a=0 and x¹ is not present,when f=1, d=1 and e=0, andwhen e=1, f=0 and x² is not present.

Particularly useful phosphorus-containing compounds (I) are those ofstructural formulas (1)-(6):

in which R¹, R², Me and v have the aforestated meanings. In theforegoing structural formulas, R¹ is preferably H, R² is preferably H(except in compounds of structural formula 1 where only R¹ may be H) oralkyl of from 1 to 8 carbon atoms and Me is preferably lithium, sodium,potassium, magnesium, calcium, barium, aluminum, titanium, vanadium,chromium, molybdenum, iron, nickel, cobalt, copper or zinc.

Illustrative of the alkylatable phosphorus-containing starting reactantsherein are phosphonic acid (phosphorous acid); hypophosphorous acid;phosphinic acid, phosphinous acid; esters of the foregoing such asphosphonic acid tert-butyl ester; phosphonic acid di-tert-butyl ester,phosphonic acid methyl ester, phosphonic acid phenyl ester, phosphinicacid tert-butyl ester, methylphosphinic acid phenyl ester,benzenephosphinic acid phenyl ester, and the like; and, metal salts ofthe foregoing such as sodium hypophosphite, calcium hypophosphite, zinchyposphosphite, aluminum hypophosphite, sodium phosphite, calciumphosphite, zinc phosphite, aluminum phosphite, ferric phosphite, sodiumbenzenephosphinate, sodium methylphosphinate, and the like.

In another embodiment of the invention, the reactant which generatesalkene or cycloalkene in situ is represented by the general formulaR⁴—X  (II)wherein:

R⁴ is alkyl of up to 30 carbon atoms or cycloalkyl of from 3 to 12carbon atoms; and,

X is halogen,

in which R⁵ and R⁶ each independently is H, alkyl of up to 30 carbonatoms, cycloalkyl of from 3 to 12 carbon atoms or aryl of from 6 to 20carbon atoms and g is 0 or 1.

In reactant (II), R⁴ is preferably branched alkyl since branching morereadily provides alkene alkylating agent.

Illustrative of useful halides R⁴—X are 2-chloro-2-methylpropane,2-bromo-2-methylpropane, 2-chloropropane, 2-bromopropane, tert-amylchloride, tert-amyl bromide, and the like.

Useful alcohols of structure R⁴—OH include tert-butyl alcohol, tert-amylalcohol, isopropyl alcohol, 2-butanol, 2-buten-1-ol and2-methyl-3-buten-2-ol. Likewise suitable are cyclic alcohols, inparticular, 1-methylcyclopentanol, 1-methycycloheptanol,1-methylcyclooctanol and 1-methylcyclodecanol.

Useful esters of the structures

include tert-butyl acetate, phosphoric acid tert-butyl ester, phosphonicacid tert-butyl ester, phosphonic acid di-tert-butyl ester,diisobutylphosphinic acid tert-butyl ester, isopropyl tosylate,isopropyl mesylate, and the like.

As free-radical initiators, advantageous use is made of azo compounds.Preferably, the azo compounds are cationic and/or non-cationic azocompounds. Preferably, as cationic azo compounds, use is made of2,2′-azobis(2-amidinopropane) dihydrochloride or2,2′-azobis(N,N-dimethyleneisobutyramidine) dihydrochloride. Preferably,as non-cationic azo compounds, use is made of azobis(isobutyronitrile)(AIBN), 4,4′-azobis(4-cyanopentanoic acid) or2,2′-azobis(2-methylbutyronitrile).

Preferably, as free-radical initiators, use is also made of inorganicperoxide and/or organic peroxide free-radical initiators.

Preferably, as inorganic peroxide free-radical initiators, use is madeof hydrogen peroxide, ammonium peroxodisulfate and/or potassiumperoxodisulfate.

Preferably, as organic peroxide free-radical initiators, use is made ofdibenzoyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoateand/or peracetic acid.

Preferably, UV light initiation alone or in combination withabove-mentioned initiators is employed.

Preferably, the reaction is carried out in the presence of carboxylic ormineral acid. Particularly preferably, the carboxylic acid is aceticacid and the mineral acid is sulfuric acid.

Preferably, the reaction is carried out at a temperature of from about25 to about 130° C. Particularly preferably, the reaction is carried outat a temperature of from about 60° C. to about 120° C. Preferably, thereaction is carried out at atmospheric pressure. If generated in situ,an alkene tends to evaporate from the reaction vessel prior to reactingwith P—H in which case a condenser can be used in order to return thealkene to the reaction vessel. Alternatively, a pressure of about 1-2atmospheres can be applied in order to prevent evaporation of thealkene.

The present invention also relates in particular to a process in whichhypophosphorous acid or sodium hypophosphite is reacted with tert-butylalcohol or tert-butyl acetate in the presence of azo free-radicalinitiator or in the presence of a peroxide free-radical initiator togive diisobutyl phosphinic acid and/or sodium salt thereof as mainproduct.

The invention also relates to the use of the dialkyphosphinic acidsand/or alkali metal salts thereof obtained by the above-describedprocess for preparing salts of such metals as Mg, Ca, Al, Zn, Fe(II),Fe(III), Cu(II), Zr(IV). These salts find use as flame retardants forthermoplastic polymers such as poly(ethylene terephthalate),polybutylene terephthalate), polystyrene, polyamide, polyethylene,polypropylene, and the like, and thermoset resins such as epoxy,phenolic or bismaleimide resins, and the like. The dialkylphosphinicacids and/or alkali metal salts thereof obtained by the above-describedprocess are also used as intermediates in the pharmaceutical industry.

The process of the invention is illustrated by the examples whichfollow.

Example 1

Into a 250 ml three-necked flask equipped with condenser, additionfunnel, magnetic stirrer and thermometer were charged 47.79 g (0.362mol) 50% commercial hypophosphorous acid, 45.94 g (0.395 mol) tert-butylacetate and 3.2 g AIBN. The reaction mixture was heated to 61° C. andstirred for 3 hours. Thereafter, a second portion of 8.7 g AIBN inacetic acid solution was gradually added while the temperature of thereaction mixture was slowly raised to 84° C. over the course of 11hours. After addition was complete, ³¹P NMR analysis indicated theformation of 8% di-isobutylphosphinic acid, 63% isobutylphosphinic and29% hypophosphorus acid. The reaction mixture was either neutralized byaqueous sodium hydroxide solution and then treated with aqueous aluminumhydroxide or directly reacted with aluminum oxide. The resulting whiteprecipitate was filtered out, washed with water and dried in an oventhus providing 23 g aluminum salt of isobutylphosphinic acid. The motherliquor can, if desired, be recycled and used for preparing anotherquantity of product.

Example 2

Into a 500 ml three-necked flask equipped with condenser, additionfunnel, magnetic stirrer and thermometer were charged 65.80 g (0.498mol) 50% commercial hypophosphorous acid and 79.92 g (1.08 mol)tert-butyl alcohol. The reaction mixture was heated to 70° C. andaddition of 2.06 g AIBN in 35 g acetic acid solution begun. After 6hours, the addition was complete. The mixture contained 50%isobutylphosphinic acid and 50% hypophosphorus acid as determined by ³¹PNMR. The mixture was treated with a second portion of 5.5 g AIBN and 5.7g t-butyl peroxybenzoate in acetic acid while the temperature wasgradually increased to 97° C. over the course of 10 hours. Afteraddition was complete, the mixture was found to contain 75%di-isobutylphosphinic acid, 20% isobutylphosphinic acid and 5%isobutylphosphonic acid. The mixture was dried in a rotavapor undervacuum at 75° C. to remove water and solvent and washed with warm waterthree times. The upper oily phase was separated and dried in a rotavaporunder vacuum at 75° C. 57.5 g. The oily material was collected andcrystallized at room temperature. The yield based on hypophosphorousacid was 65% without recycling the mother liquid. The mother liquid can,if desired, be recycled and used for preparing another quantity ofproduct.

Example 3

Into a 2 L four-necked flask equipped with condenser, addition funnel,mechanical stirrer and thermometer were charged 321.35 g (3.03 mol)sodium hypophosphite monohydrate and 637 g acetic acid. After thesolution became clear, 149.33 g sulfuric acid was gradually added to themixture and a slurry was observed. A solution comprised of 458.18 g(6.186 mol) tert-butanol, 107.85 g acetic acid and 18.63 g (0.13 mol)di-tert-butyl peroxide was slowly added at a temperature of from 104 to110° C. over 14.5 hours. Analysis of the mixture by ³¹P NMR showed it tocontain 58 mol % diisobutylphosphinic acid and 42 mol %monoisobutylphosphinic acid. There was no measurable amount ofhypophosphorus acid as determined by ³¹P NMR analysis. A portion of thesolvent was then removed. Another solution comprising 98.80 g (1.33 mol)tert-butanol, 5.87 g (0.040 mol) di-tert-butyl peroxide and 23.7 gacetic acid was added to the reaction mixture at a temperature of from103 to 111° C. over 7 hours. ³¹P NMR analysis indicated a mixture of 73%diisobutylphosphinic acid and 25% monoisobutylphosphinic acid with theremainder made up of monoisobutylphosphonate acid and phosphorus acid.

Example 4

The alkylated product mixture obtained in Example 3, supra, was filteredand the solvents were stripped out in a rotavapor under vacuum. Theliquid mixture was then consecutively washed with 200 mL water, 200 mL2.7% sodium carbonate three times and 200 mL water twice. The upperlayer was separated and dried in a Rotavapor under vacuum. The materialcrystallized upon standing at room temperature to provide 350 g purediisobutylphosphinic acid. The yield was 65%.

Example 5

A portion of the above pure diisobutylphosphinic acid (135.01 g, 0.758mol) was mixed with water and neutralized with dilute aqueous sodiumhydroxide solution. The neutralized product was then mixed with asolution of 61.83 g (0.256 mol) AlCl₃ 6H₂O in 2 L water. A large amountof white precipitate was observed. The precipitate was filtered anddried to a constant weight in an oven at 105° C. A white powder,aluminum salt of diisobutylphosphinic acid, of 139.43 g was obtained.The yield was 98.9%.

Example 6

Into a 1 L four-necked flask equipped with condenser, addition funnel,mechanical stirrer and thermometer were charged 187.52 g (1.77 mol)sodium hypophosphite monohydrate and 294 g acetic acid. After thesolution became clear, 88.18 g sulfuric acid was gradually added theretoand a slurry was observed. A solution comprised of 150.81 g (2.03 mol)tert-butanol, 16.97 g acetic acid and 6.35 g (0.043 mol) di-tert-butylperoxide was slowly added at a temperature range of from 111 to 118° C.over 6 hours. Analysis of the mixture by ³¹P NMR showed the mixture toconsist of 13 mol % diisobutylphosphinic acid, 72 mol %monoisobutylphosphinic acid and 13% hyposphosphorus acid. Anothersolution comprising 156.577 g (2.11 mol) tert-butanol, 11.86 gdi-tert-butyl peroxide (0.081 mol) and 160.29 g acetic anhydride wasthen added to the reaction mixture at a temperature of 104 to 111° C.over 14.5 hours while 13.71 g sulfuric acid was added from a secondfunnel. A mixture of 87.5% diisobutylphosphinic acid, 9.5%monoisobutylphosphinic acid, 1.6% monoisobutylphosphonic acid and 1.4%phosphorus acid was obtained.

Example 7

The alkylated product mixture obtained in Example 6, supra, was firstfiltered and then stripped in a Rotavapor at a bath temperature of 100°C. A solution of 302 g was obtained. Part of this solution (233 g, total1.37 mol P) was neutralized with diluted sodium hydroxide and added to2.5 L 4% aqueous aluminum chloride (0.435 mol AlCl₃ 6H₂O). The resultingwhite precipitate was filtered and dried in an oven at 75° C. overnight.214 g of white powder, aluminum salts of diisobutylphinic acid,monoisobutylphosphinic acid and monoisobutylphosphonic acid, wasobtained.

Example 8

Into a 2 L four-necked flask equipped with condenser, addition funnel,mechanical stirrer and thermometer were charged 211.76 g (2.00 mol)sodium hypophosphite monohydrate and 317 g acetic acid. After thesolution became clear, 106.97 g sulfuric acid was gradually added to themixture and a slurry was observed. The mixture was then heated to 120°C. A solution comprised of 243.19 g (2.09 mol) tert-butyl acetate and7.35 g (0.050 mol) di-tert-butyl peroxide was slowly added at atemperature of 115 to 120° C. over 5 hours. Analysis of the mixture by³¹P NMR showed the mixture contained 11 mol % diisobutylphosphinic acid,72 mol % monoisobutylphosphinic acid and 17 mol % hypophosphorus acid. Afurther 20.12 g sulfuric acid was added. Another solution comprising310.73 g (2.68 mol) tert-butyl acetate and 13.10 g (0.090 mol)di-tert-butyl peroxide was added to the reaction mixture at atemperature of 114 to 120° C. over 10 hours. ³¹P NMR analysis indicatedthe mixture to contain 88% diisobutylphosphinic acid and 10%monoisobutylphosphinic acid with the remainder made up ofmonoisobutylphosphonate acid and phosphorus acid.

Example 9

The alkylated product mixture obtained in Example 8, supra, was filteredand the solvents were stripped out in a rotavapor under vacuum. Theliquid was mixed with 100 mL toluene and consecutively washed by 200 mLwater, 150 mL 3.8% sodium carbonate three times and 100 mL water twicerespectively. The upper layer was separated and dried at a Rotavaporunder vacuum. The layer crystallized upon standing at room temperatureto provide 288 g pure diisobutylphosphinic acid. The yield was 81%.

While the process of the invention has been described with reference tocertain embodiments, it will be understood by those skilled in the artthat various changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best modecontemplated for carrying out the process of the invention but that theinvention will include all embodiments falling within the scope of theappended claims.

1. A process for alkylating a phosphorus-containing compound to providean alkylated phosphorus-containing compound which comprises alkylatingphosphorus-containing compound possessing at least onephosphorus-hydrogen

alkylatable site with reactant which generates alkene and/or cycloalkenealkylating agent in situ in the presence of initiator, the alkyleneand/or cycloalkylene alkylating agent alkylating thephosphorus-containing component to provide alkylatedphosphorus-containing product wherein phosphorus-containing compound isrepresented by general formula (I):

wherein: x¹, where present, is

and x², where present, is

in which R¹ is H, alkyl of up to 30 carbon atoms, cycloalkyl of from 3to 12 carbon atoms or aryl of from 6 to 20 carbon atoms; Me is a metalhaving a valence v of 1, 2, 3 or 4; R² is H, alkyl of up to 30 carbonatoms, cycloalkyl of from 3 to 12 carbon atoms or aryl of from 6 to 20carbon atoms; and, a, b, c, d, e and f each independently is 0 or 1,provided, when a=1, c=1 and b=0, when b=1, a=0 and x¹ is not present,when f=1, d=1 and e=0, and when e=1, f=0 and x² is not present, and thereactant which generates alkene or cycloalkene in situ is represented bygeneral formula (II):R⁴—X  (II) wherein: R⁴ is alkyl of up to 30 carbon atoms or cycloalkylof from 3 to 12 carbon atoms; and,

in which R⁵ and R⁶ each independently is H, alkyl of up to 30 carbonatoms, cycloalkyl of from 3 to 12 carbon atoms or aryl of from 6 to 20carbon atoms and g is 0 or
 1. 2. The process of claim 1 whereinphosphorous-containing compound (I) is selected from the group (1)-(6)consisting of:

in which R¹, R², Me and v have the aforestated meanings.
 3. The processof claim 2 wherein in phosphorus-containing compounds (1)-(6), R¹ is Hand Me is lithium, sodium, potassium, magnesium, calcium, barium,aluminum, titanium, vanadium, chromium, molybdenum, iron, cobalt,nickel, copper or zinc.
 4. The process of claim 3 wherein inphosphorus-containing compounds (2) and (3), R² is H.
 5. The process ofclaim 1 wherein phosphorus-containing compound (I) is at least onemember selected from the group (1)-(6) consisting of:

in which R¹, R², Me and v have the aforestated meanings.
 6. The processof claim 5 wherein in phosphorus-containing compounds (1)-(6), R¹ is Hand Me is lithium, sodium, potassium, magnesium, calcium, barium,aluminum, titanium, vanadium, chromium, molybdenum, iron, cobalt,nickel, copper or zinc.
 7. The process of claim 6 wherein inphosphorus-containing compounds (2) and (3), R² is H.
 8. The process ofclaim 1 wherein the phosphorus-containing compound is at least onemember of the group consisting of phosphonic acid, hypophosphorous acid,phosphinic acid, phosphinous acid, phosphonic acid tert-butyl ester,phosphonic acid di-tert-butyl ester, phosphonic acid methyl ester,phosphonic acid phenyl ester, phosphinic acid tert-butyl ester,methylphosphinic acid phenyl ester, benzenephosphinic acid phenyl ester,sodium hypophosphite, calcium hypophosphite, zinc hyposphosphite,aluminum hypophosphite, sodium phosphite, calcium phosphite, zincphosphite, aluminum phosphite, ferric phosphite, sodiumbenzenephosphinate and sodium methylphosphinate.
 9. The process of claim1 wherein the reactant which generates alkene or cycloalkene in situ isat least one member of the group consisting of tert-butyl alcohol,tert-amyl alcohol, isopropyl alcohol, 2-butanol, 2-buten-1-ol,2-methyl-3-buten-2-ol, 1-methylcyclopentanol, 1-methycycloheptanol,1-methylcyclooctanol, 1-methylcyclodecanol, tert-butyl acetate,phosphoric acid tert-butyl ester, phosphonic acid tert-butyl ester,phosphonic acid di-tert-butyl ester, diisobutylphosphinic acidtert-butyl ester, isopropyl tosylate and isopropyl mesylate.
 10. Theprocess of claim 8 wherein the reactant which generates alkene orcycloalkene in situ is at least one member of the group consisting oftert-butyl alcohol, tert-amyl alcohol, isopropyl alcohol, 2-butanol,2-buten-1-ol, 2-methyl-3-buten-2-ol, 1-methylcyclopentanol,1-methycycloheptanol, 1-methylcyclooctanol, 1-methylcyclodecanol,tert-butyl acetate, phosphoric acid tert-butyl ester, phosphonic acidtert-butyl ester, phosphonic acid di-tert-butyl ester,diisobutylphosphinic acid tert-butyl ester, isopropyl tosylate andisopropyl mesylate.
 11. The process of claim 1 wherein the initiator isat least one free radical initiator, UV light or a combination thereof.12. The process of claim 11 wherein the free radical initiator is atleast one azo compound, inorganic peroxide and/or organic peroxide. 13.The process of claim 11 wherein the free radical initiator is at leastone member selected from the group consisting of2,2′-azobis(2-amidinopropane) dihydrochloride,2,2′-azobis(N,N′-dimethyleneisobutyramidine) dihydrochloride,azobis(isobutyronitrile), 4,4′-azobis(4-cyanopentanoic acid),2,2′-azobis(2-methylbutyronitrile), hydrogen peroxide, ammoniumperoxodisulfate, potassium peroxodisulfate, dibenzoyl peroxide,di-tert-butyl peroxide and peracetic acid.
 14. The process of claim 1carried out in the presence of carboxylic acid and/or mineral acid. 15.The process of claim 1 wherein the alkylation reaction is carried out ata temperature of from about 25° C. to about 130° C. and a pressureranging from about atmospheric up to about 2 atmospheres.
 16. Theprocess of claim 5 wherein phosphorus-containing compound (I) is atleast one member selected from the group consisting of (2) and (3), thealkylated reaction product thereafter being converted to thecorresponding metal salt.
 17. The process of claim 16 wherein the metalof said metal salt is selected from the group consisting of Mg, Al, Zn,Fe(II), Fe(III), Cu(II) and Zr(IV).
 18. The process of claim 1 wherein:the phosphorus-containing compound is at least one member of the groupconsisting of phosphonic acid, hypophosphorous acid, phosphinic acid,phosphinous acid, phosphonic acid tert-butyl ester, phosphonic aciddi-tert-butyl ester; phosphonic acid methyl ester, phosphonic acidphenyl ester, phosphinic acid tert-butyl ester, methylphosphinic acidphenyl ester, benzenephosphinic acid phenyl ester, sodium hypophosphite,calcium hypophosphite, zinc hyposphosphite, aluminum hypophosphite,sodium phosphite, calcium phosphite, zinc phosphite, aluminum phosphite,ferric phosphite, sodium benzenephosphinate and sodiummethylphosphinate, the reactant which generates alkene or cycloalkene insitu is at least one member of the group consisting of tert-butylalcohol, tert-amyl alcohol, isopropyl alcohol, 2-butanol, 2-buten-1-ol,2-methyl-3-buten-2-ol, 1-methylcyclopentanol, 1-methycycloheptanol,1-methylcyclooctanol, 1-methylcyclodecanol, tert-butyl acetate,phosphoric acid tert-butyl ester, phosphonic acid tert-butyl ester,phosphonic acid di-tert-butyl ester, diisobutylphosphinic acidtert-butyl ester, isopropyl tosylate and isopropyl mesylate; and, theinitiator is at least one free radical initiator, UV light or acombination thereof.